[Haskell-cafe] Non-traversable foldables
lemming at henning-thielemann.de
Fri Oct 9 10:45:01 EDT 2009
On Fri, 9 Oct 2009, Martijn van Steenbergen wrote:
> Hallo café,
> Can anyone think of datatypes that are Foldable but not Traversable?
> If not, what is the purpose of having a separate Foldable class?
Recently I wondered, why Foldable is superclass of Traversable, since I
have examples where 'traverse' makes sense, but 'fold' not.
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